REPORT ON THE CUMACEA. 49 



an elevated ridge, which in the anterior part is armed with four strong denticles and 

 some ciliated bristles issuing between the denticles. Along the inner edge, moreover, 

 a series of rather strong, cdiated setse are present, increasing in length anteriorly. The 

 ischial joint is distinctly defined though very short, and armed on the inner edge with 

 a strong denticle. From the inner edge of the succeeding joint two similar denticles 

 arise. The antepenultimate joint is very slender and elongate, considerably longer than 

 the two outer joints taken together, and only provided with a few simple bristles. The 

 terminal joint is a little longer than the penultimate and conical in form, with some 

 hair-like bristles, the one issuing from the tip being the longest. The exopodite is 

 exactly of the same structure as that of the first pair of legs. 



The three posterior pairs of legs (figs. 9—11) are all simple, without any trace of 

 exopodites, and of essentially the same structure. Of the joints the basal is by far the 

 largest, in the two anterior pairs even longer than all the others taken together. The 

 ischial joint is very short, scarcely longer than broad, whereas the two succeeding joints 

 are more elongate and about equal in size. The two last joints are suddenly very much 

 smaller, and taken together scarcely as long as the preceding joint. These legs are 

 rather richly supplied with ciliated bristles, esjsecially along the inner edge. But there 

 is a number of bristles issuing from the outer part of the legs, which differ essentially 

 from the rest in being considerably stronger, unciliated, and terminating in a finely 

 annulated, somewhat curved point. Five such peculiarly modified bristles are present 

 on each leg, four of which arise from the outer corner of the antepenultimate joint, and 

 the fifth from the penultimate one. At the tip of the terminal joint is affixed a claw- 

 Hke spine and a simple bristle. As to the relative size of these legs, the two anterior 

 pairs are nearly of the same length, whereas the last pair (fig. 11) are considerably 

 smaller, chiefly on account of the shortening of the basal joint. 



The marsupial pouch, as in other Cumacea, is composed of four pairs of large plates 

 arising from the bases of the second pair of gnathopoda and the three anterior pairs of 

 legs. They were fully developed in only one of the specimens, which was somewhat 

 crushed, and therefore selected for dissection. The marsupial pouch in this specimen 

 contained a number of embryos, of which I have figured one in four different aspects 

 (figs. 14—17), to be described below. 



The telson (see fig. 12) is distinctly defined and about twice as long as the last 

 caudal segment. It has a rather narrow, lageniform shape, the basal part, containing 

 the terminal portion of the intestine, being somewhat dilated and cylindrical, whereas 

 the outer part is very narrow, gradually tapering, and nearly twice as long as the basal 

 part. At the junction between the two, on the lower side, the anal orifice occurs. The 

 basal part is quite smooth, whereas the terminal is armed at the edges with about nine 

 pairs of denticles, somewhat irregularly arranged, and at the tip with two denticles of a 

 quite similar appearance. 



(ZOOL. CHALL. EXP, PART LV. 1887.) Ill 7 



